Since our eyes naturally perceive depth, it is seen as a disadvantage that most display systems are two dimensional. Furthermore, there are many applications of displays where the realism of depth would improve the effectiveness of the display. Thus many attempts have been made to create display systems with depth.
A number of display systems that present an image of depth have been developed. One class of such displays requires the viewer to wear some form of eye shield system by which various means allows the viewer's two eyes to see different images that are concurrently displayed on the same two dimensional screen. However, many users find it unsatisfactory to wear eye shields, while the method of providing two different images on the same screen is cumbersome and inconvenient for many applications.
A related but different class of displays presents a different image to each eye by means of a binocular image system in close proximity to both eyes. This method, however, is restricted in the number of viewers who can use the system and again many users find it unsatisfactory and uncomfortable to use.
A third class of display uses modifications of the two dimensional screen surface wherein two images are created on the screen, but by manipulation of multiple refractors on the screen, for a viewer in the correct position one image is refracted into the right eye, and the other image is refracted into the left eye.
This system requires the users to be carefully placed, is inflexible and has not found favour with many users.
The major problems with these systems were overcome by the innovative screen techniques disclosed in PCT Patent Application No's. PCT/NZ98/00098 and PCT/NZ99/00021 which detail a screen system producing a perception of depth comprising at least two screens placed such that their axes are approximately co-linear, with each screen separated from the other in the direction of the normal, wherein an image, or part of an image, displayed on one or more screens can be selectively made transparent, opaque or partially opaque as desired.
It has been found however that even with these types of screens there are some applications where the operator needs more control of the images, such as with computer games and other interactive programs—for example training programs.
All references, including any patents or patent applications, cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents forms part of the common general knowledge in the art, in New Zealand or in any other country.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.